I'd swap any future chassis, suspension or performance upgrades for a little more ground clearance!
If you have the standard Plus 4 tyres of 195/60 R15 you can gain 1cm by fitting 195/65 R15 tyres.1cm may not seem like much but it will take the total ground clearance on a Plus 4 to over 10cm which will get you over most speed humps without touching.